Method and system for detecting retroreflectors

ABSTRACT

An optical device that may include a sighting portion including an optical axis; an electromagnetic beam source coupled to said sighting portion, electromagnetic beam source facilitates generating a source beam including an axis that is substantially parallel to said optical axis; an optical surface coupled to said electromagnetic beam source; and a frequency filter coupled within said sighting portion.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.12/232,943 entitled METHOD AND SYSTEM FOR DETECTING RETROREFLECTORS,filed Sep. 26, 2008 which claims priority to U.S. Provisional PatentApplication No. 60/975,924, filed Sep. 28, 2007 entitled OPTICAL DEVICE,the entire contents of which are hereby incorporated by reference.

BACKGROUND OF THE INVENTION

Retroreflectivity is a term that describes an object's ability toreflect a wave front such as light, electro-magnetic waves or otherforms of radiation back to the source along a path or vector that issubstantially parallel to the vector of the source wave front path.

Retroreflectivity is a phenomenon that may occur in nature. One exampleof natural occurring retroreflectivity is the ability of an animal'seyes to reflect light such that the eyes appear to glow. Thisretroreflectivity occurs because the eyes of most animals include afocusing lens and a partially reflective layer of tissue near or part ofthe retina that is positioned substantially near a focal plane of thefocusing lens. As a result, the eyes of animals may reflect a portion ofthe light entering the eye back to the light source on a path that issubstantially parallel to the light source path. As such, objects thatinclude a lens and a surface having some degree of reflectivity that ispositioned substantially near a focal plane of the lens, may be definedas a retroreflector.

Retroreflectors may also be manufactured. Some examples of artificialretroreflective instruments include reflective highways signs, bicyclereflectors and corner reflectors. One known example of a cornerreflector is a surveyor's reflecting prism that may be used with asurveyor's total station to calculate a distance between the totalstation and the prism. Other retroreflector examples may be opticalinstruments that include a lens and a surface that has a degree ofreflectivity that is positioned substantially near a focal plane of thelens. Examples of such optical instruments may be rifle scopes,binoculars and cameras.

BRIEF DESCRIPTION OF THE INVENTION

In one exemplary embodiment, an optical device may be provided. Theoptical device may include a sighting portion including an optical axis;an electromagnetic beam source coupled to said sighting portion,electromagnetic beam source facilitates generating a source beamincluding an axis that is substantially parallel to said optical axis;an optical surface coupled to said electromagnetic beam source; and afrequency filter coupled within said sighting portion.

In another exemplary embodiment, a method of detecting retroreflectorsusing an optical device may be provided. The method may includegenerating an electromagnetic source beam that has a first frequency;shaping the electromagnetic source beam; channeling the shapedelectromagnetic source beam towards a retroreflector; channeling areflected shaped electromagnetic beam that is reflected by theretroreflector through a frequency filter; and displaying the reflectedshaped electromagnetic beam.

In yet another embodiment, a means for detecting retroreflectors may beprovided. The means may include a means for generating anelectromagnetic source beam that has a first frequency; a means forshaping the electromagnetic source beam; a means for channeling theelectromagnetic source beam towards at least one retroreflector; a meansfor filtering electromagnetic beams that have second frequencies thatare substantially different than the first frequency of theelectromagnetic source beam.

BRIEF DESCRIPTION OF THE DRAWINGS

Advantages of embodiments of the present invention will be apparent fromthe following detailed description of the exemplary embodiments. Thefollowing detailed description should be considered in conjunction withthe accompanying figures in which:

FIG. 1 is a cross-sectional side view of an optical device; and

FIG. 2 is an exploded perspective view of the optical device shown inFIG. 1.

DETAILED DESCRIPTION OF THE INVENTION

Aspects of the present invention are disclosed in the followingdescription and related figures directed to specific embodiments of theinvention. Those skilled in the art will recognize that alternateembodiments may be devised without departing from the spirit or thescope of the claims. Additionally, well-known elements of exemplaryembodiments of the invention will not be described in detail or will beomitted so as not to obscure the relevant details of the invention.

As used herein, the word “exemplary” means “serving as an example,instance or illustration.” The embodiments described herein are notlimiting, but rather are exemplary only. It should be understood thatthe described embodiment are not necessarily to be construed aspreferred or advantageous over other embodiments. Moreover, the terms“embodiments of the invention”, “embodiments” or “invention” do notrequire that all embodiments of the invention include the discussedfeature, advantage or mode of operation.

FIG. 1 is a cross-sectional side view of an optical device 100. FIG. 2is an exploded perspective view of optical device 100. In oneembodiment, optical device 100 may be configured for hand-held use. Inanother embodiment, optical device 100 may be configured forweapon-mounted applications, such as, but not limited to, a rifle scope.In yet another alternative embodiment, optical device 100 may be mountedon a stand such as, but not limited to, a tripod and/or any other typeof support structure that enables optical device 100 to function asdescribed herein. Alternative embodiments of optical device 100 mayinclude, but not limited to, a sighting scope that includes a reticle,an automated gimbal mount for remote fixed-area scanning or vehiclemounting, a binocular configuration for visible and non-visible imageassessment, imaged to a photoelectric transducer device for videodisplay, output and automated image processing, and target designationillumination optimized for ambient energy intensity levels.

Optical device 100 may include a sighting portion 102 and anelectromagnetic wave source, or laser source 104, coupled to sightingportion 102 using a chassis 103. In the exemplary embodiment, chassis103 facilitates aligning laser source 104 with respect to sightingportion 102. Moreover, chassis 103 may facilitate coupling opticaldevice 100 to other objects for mounting purposes. Sighting portion 102may have a substantially cylindrical shape and include an ocular end106, an objective end 108 and a centerline axis, or optical axis 109.Alternatively, sighting portion 102 may have any type of shape thatenables optical device 100 to function as described herein. In theexemplary embodiment, ocular end 106 may face a user 110 and objectiveend 108 may face an objective, or target 112. For exemplary purposes ofdescribing the exemplary embodiments of the present invention, target112 in the exemplary embodiment may be a retroreflector such as, but notlimited to, an optical scope, a camera and/or a pair of binoculars. Morespecifically, target 112 may include a lens 114 and a reflective surface116 to facilitate retroreflecting electromagnetic waves back towards thewave source, as described in more detail below.

Sighting portion 102, and more specifically objective end 108, mayinclude a first objective optical surface 118 that may be coupled withinsighting portion 102. Sighting portion 102 may also include a secondoptical surface 124 that may be coupled therein, wherein second opticalsurface 124 may facilitate focusing the electromagnetic waves that arereceived through objective end 108 of optical device 100. Sightingportion 102 facilitates magnifying objects viewed by user 110 alongoptical axis 109 of sighting portion 102, wherein the objects may bepositioned a distance downfield from optical device 100.

Moreover, sighting portion 102 may also include a band-pass filter 126coupled therein, wherein band-pass filter 126 may be positioned adjacentsecond optical surface 124 such that the electromagnetic waves may bechanneled from second optical surface 124 towards user 110, and morespecifically, towards band-pass filter 126. In one embodiment, band-passfilter 126 may be tunable. In another alternative embodiment, band-passfilter 126 may be a rotatable tunable band-pass filter. In yet anotheralternative embodiment, band-pass filter 126 may be a fixed band-passfilter that may facilitate filtering a specific laser frequency. In theexemplary embodiment, band-pass filter 126 facilitates filtering, orpreventing, a plurality of electromagnetic waves 127 that may havefrequencies that do not substantially match the frequency set on theband-pass filter 126 from passing through band-pass filter 126. As aresult, electromagnetic waves that have a frequency that substantiallymatches the frequency set on band-pass filter 126 may be channeledthrough band-pass filter 126 towards a photoelectric transducer 128, asdescribed in more detail below. In the exemplary embodiment, band-passfilter 126 may be adjustable to enable user 110 to adjust, or select,which beam frequencies are filtered and which beam frequencies are notfiltered.

Photoelectric transducer 128 may be positioned adjacent to band-passfilter 126 such that the electromagnetic waves that are channeledthrough band-pass filter 126 may impinge on photoelectric transducer128, which facilitates generating an image that may be observed by user110. In one embodiment, photoelectric transducer 128 may be aphotocathode. Moreover, an image intensifier 129 may be coupled withinsighting portion 102 and positioned adjacent photoelectric transducer128 such that image intensifier 129 is positioned between ocular end 106and photoelectric transducer 128.

Turning to laser source 104, in the exemplary embodiment, laser source104 facilitates generating an electromagnetic wave, or beam.Specifically, laser source 104 may include a beam generation portion 130and a beam emission end 132 coupled in communication with beamgeneration portion 130. Laser source 104 facilitates emitting a sourcebeam 134 that may be channeled though beam emission end 132 such thatsource beam 134 may exit laser source 104 on a first source beam vector135. In one embodiment, source beam 134 may be a collimated beam ofelectromagnetic wave energy. In another alternative embodiment, sourcebeam 134 may be a non-collimated beam of electromagnetic energy. In yetanother alternative embodiment, source beam 134 may be any type of beamor electromagnetic wave that enables optical device 100 to function asdescribed herein.

In the exemplary embodiment, a shape forming optical surface 138 may becoupled to laser source 104 such that shape forming optical surface 138may be positioned downfield from laser source 104. Shape forming opticalsurface 138 facilitates forming a shape of the source beam 134. In oneembodiment, the shape of source beam 134 may be a substantially verticalstripe. Alternatively, shape forming optical surface 138 may facilitateforming any type of shape of source beam 134 that enables optical device100 to function as described herein.

In one embodiment, a prism 140 may be coupled to both laser source 104and sighting portion 102 to enable monostatic operation of opticaldevice 100, as described in more detail below. Specifically, prism 140may have a first end that has a first angled side 142 and a second endthat has a second angled side 144. In one embodiment, prism 140 may havea substantially rhomboidal shape. Alternatively, prism 140 may have anyshape that enables optical device 100 to function as described herein.In the exemplary embodiment, prism 140 may be oriented such that thefirst end may be positioned substantially within first source beamvector 135 and the second end may be positioned substantially withinoptical axis 109. Specifically, first and second angled sides 142 and144 of prism 140 facilitate reflecting source beam 134 from first sourcebeam vector 135 to a second source beam vector 148 that may besubstantially co-axial with optical axis 109, as described in moredetail below. It should be understood by a person having ordinary skillin the art that reflecting source beam 134 along second source beamvector 148 that may be substantially co-axial with optical axis 109 maybe defined as monostatic operation.

In an alternative embodiment, optical device 100 may not include prism140 such that laser source 104 may emit source beam 134 along firstsource beam vector 135 that may be substantially parallel to opticalaxis 109. It should be understood by a person having ordinary skill inthe art that emitting source beam 134 along first source beam vector 135that may be substantially parallel with optical axis 109 may be definedas bistatic operation.

During operation, a user may operate optical device 100 such thatobjective end 108 may face the potential target 112, which may bepositioned downfield from user 110. User 110 may look through opticaldevice 100 such that user 110 may look downfield along optical axis 109.User 110 may activate laser source 104 such that source beam 134 may beemitted therefrom. In one embodiment, laser source 104 emits a sourcebeam that has a first frequency that is known to user 110. In anotherembodiment, source beam 134 may be either a visible beam or anon-visible beam.

During monostatic operation, source beam 134 may be channeled throughshape forming optical surface 138 and then reflected by first angledside 142 of prism 140, which facilitates reflecting source beam 134towards second angled side 144 of prism 140. Second angled side 144facilitates reflecting source beam 134 along second source beam vector148 that may be substantially co-axial to optical axis 109. Monostaticoperation may facilitate detecting targets 112 that may be positioned atsubstantially close ranges with respect to optical device 100. Moreover,monostatic operation may also facilitate detecting targets 112 duringthe day when background radiation energy may be substantially higherthan nighttime background radiation energy.

Alternatively, during bistatic operation, laser source 104 may emitsource beam 134 such that source beam 134 may be channeled through shapeforming optical surface 138 and then downrange along first source beamvector 135, wherein first source beam vector 135 may be substantiallyparallel to optical axis 109. Bistatic operation may facilitate reducingsaturation of photoelectric transducer 128 during nighttime operationwhen the background radiation energy may be substantially lower than thedaytime background radiation energy. As a result, the saturation of theimage generated by photoelectric transducer 128 may be facilitated to bereduced.

Once laser source 104 is activated and channeling source beam 134downfield, user 110 may move optical device 100 such that source beam134 may sweep over objects positioned downfield in user's 110 field ofview. In the event source beam 134 encounters retroreflecting target112, a portion of source beam 134 may be reflected off reflectivesurface 116 and pass through lens 114 such that a reflected beam 150 isreflected back towards optical device 100 on a reflected beam vector 152that may be substantially parallel to second source beam vector 148.Reflected beam 150 may then enter optical device 100 through objectiveend 106 and pass through prism 140. First objective optical surface 118and second optical surface 124 facilitate channeling reflected beam 150towards band-pass filter 126. In the exemplary embodiment, band-passfilter 126 may be set to the first frequency of source beam 134. As aresult, band-pass filter 126 may channel electromagnetic waves that havefrequencies substantially similar to the first frequency, such asreflected beam 150, through band-pass filter 126 such that the wavesimpinge on photoelectric transducer 128. Moreover, band-pass filter 126facilitates filtering electromagnetic waves 127 that may havefrequencies that are substantially different than the first frequencyset on tunable band-pass filter. As a result, band-pass filter 126facilitates reducing the amount of electromagnetic waves that may enteroptical device 100.

Reflected beam 150 may then be channeled by band-pass filter 126 towardsphotoelectric transducer 128, wherein reflected beam 150 impingesthereon. Photoelectric transducer 128 facilitates generating a visualimage (not shown) that may be observed by user 110. The visual imagegenerated by photoelectric transducer 128 may be intensified by imageintensifier 129. As a result, user 110 may observe reflected beam 150using optical device 100. In such an event, user 100 may determine whattype of object target 112 may be. For example, in one embodiment, user110 may determine that target 112 is a bicycle or a street sign. Inanother example, however, user 110 may determined that target 112 is apair of binoculars or a scope mounted on a weapon that may be facinguser 110. As a result, optical device 100 enables user 110 to determinewhether target 112 is a threat to user 110.

In the exemplary embodiment, source beam 134 may have a specific shape,such as but not limited to, a vertical stripe, as described above. Inthe event source beam 134 encounters a reflective object such as, butnot limited to a bicycle reflector, source beam 134 may be reflectedback towards optical device 100 as reflected beam 150, wherein reflectedbeam 150 may also have a shape that is substantially similar to theshape of source beam 134. The shape of source beam 134 facilitatesconfining the beam energy channeled downfield within a shape compared toa non-shaped source beam (not shown). For example, in one embodiment,the non-shaped source beam may be a substantially conical beam that mayhave a substantially larger beam area than a shaped beam. As a result,in the event the non-shaped source beam encounters a reflective object,a non-shaped reflected beam may be reflected back towards optical device100, wherein the non-shaped reflected beam may have a substantiallyconical shaped beam that is substantially similar to the non-shapedsource beam. Therefore, the reflected non-shaped beam may have a greaterarea of beam energy than shaped source beam 134. As such, photoelectrictransducer 128 may generate an image of the non-shaped reflected beamthat may have a visual area, or image footprint, that may obstruct theuser's 110 view of the object when user 110 is looking through sightingportion 102. In such an example, photoelectric transducer 128 maygenerate an image of the non-shaped reflected beam that is either verybright or has a conical shape that may block the user's 110 view of theobject. As a result, user 110 may not be able to accurately identify thereflecting object or more specifically, identify whether the reflectingobject is a threat.

In the exemplary embodiment, shaped reflected beam 150 may have avertical striped shape that enables user 110 to see target 112 throughoptical device 100 such that user 110 may determine whether target 112is a threat to user 110. Specifically, shape forming optical surface 138facilitates confining source beam 134 to a shape such as, but notlimited to, a vertical stripe. As a result, in the event the shapedsource beam 134 encounters a reflective object, shaped reflected beam150 may be reflected back towards optical device 100. The shapedreflected beam 150 may have a smaller area of beam energy than thereflected non-shaped beam. As such, photoelectric transducer 128 maygenerate an image of shaped reflected beam 150 that may have a smallervisual area, or image footprint, than the image generated from thereflected non-shaped beam. As a result, the image generated from theshaped reflected beam 150 may not obstruct the user's 110 view of theobject. Therefore, shaped reflected beam 150 enables user 110 toaccurately identify the reflecting object, or more specifically,identify whether the reflecting object is a threat.

The foregoing description and accompanying figures illustrate theprinciples, preferred embodiments and modes of operation of theinvention. However, the invention should not be construed as beinglimited to the particular embodiments discussed above. Additionalvariations of the embodiments discussed above will be appreciated bythose skilled in the art.

Therefore, the above-described embodiments should be regarded asillustrative rather than restrictive. Accordingly, it should beappreciated that variations to those embodiments can be made by thoseskilled in the art without departing from the scope of the invention asdefined by the following claims.

1. An optical device comprising: a sighting portion comprising anoptical axis; an electromagnetic beam source coupled to said sightingportion, electromagnetic beam source facilitates generating a sourcebeam comprising an axis that is substantially parallel to said opticalaxis; an optical surface coupled to said electromagnetic beam source;and a frequency filter including a tunable band-pass filter rotatablycoupled within said sighting portion that facilitates tuning saidfrequency filter to a first frequency.
 2. An optical device inaccordance with claim 1 further comprising a prism removably coupled tosaid electromagnetic beam source and to said sighting portion, saidprism comprises a plurality of angled sides that facilitate channelingsaid source beam along a source beam vector that is substantiallyco-axial with said optical axis.
 3. An optical device in accordance withclaim 1, wherein said optical surface comprises a lens that facilitatesforming a shape of said source beam.
 4. An optical device in accordancewith claim 1, wherein said optical surface comprises a lens thatfacilitates forming a substantially vertical stripe shaped source beam.5. An optical device in accordance with claim 1, wherein saidelectromagnetic beam source comprises an electromagnetic beam generatorthat facilitates emitting at least one of a collimated beam and anon-collimated beam.
 6. An optical device in accordance with claim 1,wherein said electromagnetic beam source comprises an electromagneticbeam generator that facilitates generating a source beam that comprisesa first frequency.
 7. An optical device in accordance with claim 1,wherein said tunable band pass filter may be selectively rotated into orout of the optical axis.
 8. An optical device in accordance with claim7, wherein said tunable band-pass filter facilitates filteringelectromagnetic waves that comprise a second frequency that issubstantially different than said first frequency.
 9. An optical devicein accordance with claim 7, wherein said tunable band-pass filterfacilitates channeling electromagnetic waves that comprise a firstfrequency that is substantially similar to said first frequency of saidtunable band-pass filter.
 10. An optical device in accordance with claim1 further comprising a photoelectric transducer coupled to said sightingportion, said photoelectric transducer facilitates generating an imageof a reflected beam.
 11. An optical device in accordance with claim 1further comprising an image intensifier that facilitates intensifying animage such that said image is observable by a user.
 12. A method ofdetecting retroreflectors using an optical device, said methodcomprises: generating an electromagnetic source beam that has a firstfrequency; shaping the electromagnetic source beam; channeling theshaped electromagnetic source beam towards a retroreflector; channelinga reflected shaped electromagnetic beam that is reflected by theretroreflector through a frequency filter including selectively througha tunable band-pass filter; and displaying the reflected shapedelectromagnetic beam.
 13. A method in accordance with claim 12 furthercomprises shaping the electromagnetic source beam such that theelectromagnetic source beam includes a substantially vertical stripeshape.
 14. A method in accordance with claim 12 further compriseschanneling the electromagnetic source beam on a first vector, whereinthe first vector is substantially parallel with an optical axis of theoptical device.
 15. A method in accordance with claim 12 furthercomprises reflecting the source electromagnetic beam from a first vectorto a second vector using a prism, wherein the second vector issubstantially co-axial with an optical axis of the optical device.
 16. Amethod in accordance with claim 12 further comprises: setting thefrequency filter to a first frequency; and filtering a plurality ofelectromagnetic beams that include a plurality of second frequenciesthat are substantially different than the first frequency.
 17. A methodin accordance with claim 12 further comprising: generating an imageusing a photoelectric transducer; and displaying the image generated bythe photoelectric transducer to the user using an image intensifier. 18.A method in accordance with claim 12 further comprising generating anelectromagnetic source beam that has a first frequency, wherein theelectromagnetic source beam is at least one of a collimated beam and anon-collimated beam.